The goal of this proposed research program is to implement and evaluate complementary interventions designed to address underage alcohol, marijuana, tobacco and other drug use and abuse among Native American youth residing in and around nine contiguous Indian reservations in rural San Diego County. The application directly builds upon the successful collaboration between Indian Health Council, Inc., Prevention Research Center, and The Scripps Research Institute, with pilot and demonstration studies focusing on reducing the supply of and demand for alcohol by Native American youth through a series of environmental and individual interventions that have shown efficacy and have gained acceptability in the communities served by the clinics. The overall goal of the present proposal will be accomplished through two complementary efforts, one aimed at the community (supply) level and the other at the individual (demand) level. The community-based environmental prevention program will focus on (a) reducing underage access to alcohol and tobacco through a reward and reminder program for off-premise retail clerks and (b) tailoring, implementing and evaluating a community mobilization and awareness intervention aimed at reducing the social availability of alcohol, marijuana, tobacco, and other drugs from adults, including family members. These community-level programs will be complemented with interventions at the individual level, including implementing and evaluating a culturally tailored motivational interviewing brief intervention to reduce demand for alcohol and other drugs for American Indian youth 13-20 years of age who are substance users. We will evaluate the effectiveness of these programs by analyzing multiple data sources: (a) outcome data from a Motivational Interviewing-Psychoeducation trial among tribal youth, (b) data from school and community youth surveys on youths' self-reported substance use and related problems including driving under the influence, (c) anonymous norms and intervention awareness surveys from adults from each of the communities; and (d) law enforcement data on alcohol/drug-related events. For the purposes of evaluation, these data from the Indian Health Council catchment area will be compared to data from surveys of both non- Native and Native American youth who were not involved in the intervention activities. The research will continue to build cohorts of expert Natie American research staff and student interns for actualizing the proposed research and interventions. The team will create intervention workbooks for standardized application of the intervention techniques in other Native American communities.